1. Field
The present disclosure relates to a frit sealing system, and more particularly, to a frit sealing system to improve the quality of sealing by generating a laser beam of a normalized intensity using a homogenizer.
2. Description of the Related Art
Recently, display devices have been quickly replaced by portable thin flat display devices. The flat display devices include electroluminescent display devices which are self-luminous display devices exhibiting characteristics of a wide viewing angle, a superior contrast, and a fast response time. Thus, the electroluminescent display devices are highly expected as one of the next generation display devices. Also, organic light emitting display devices in which a light emitting layer is formed of organic matter have advantages over inorganic light emitting display devices in terms of brightness, low drive voltage, fast response time, and multicolor capabilities.
A typical organic light emitting display device has a structure in which at least one organic layer including a light emitting layer is interposed between a pair of electrodes, that is, a first electrode and a second electrode. The first electrode is formed on a substrate and functions as an anode to inject holes. The organic layer is formed above the first electrode. The second electrode having a function of a cathode to inject electrons is formed on the organic layer to face the first electrode.
In the organic light emitting display device, when moisture or oxygen comes in from a surrounding environment, the life span of a device is shortened due to oxidation or lamination of electrode material, deterioration of an efficiency of light, and the change in color of emitted light.
Thus, in the manufacturing process of the organic light emitting display device, sealing process is typically performed to prevent intrusion of moisture by isolating the device from the external environment. According to the typical sealing process, organic polymer such as polyester (PET) is laminated on the upper portion of the second electrode of the organic light emitting display device. In other instances a cover or cap is formed using metal or glass including a moisture absorbent and is filled with a nitrogen gas and then the edge of the cover or cap is capsule-sealed with a sealing member such as epoxy.
However, the mentioned methods cannot prevent the intrusion of destructive factors such as moisture or oxygen by 100%. Also, processes to embody the methods are complicated. To address the above problem, a capsule sealing method to improve close adhesion between the device substrate and the cap using frit as a sealing member is developed.
Thus, as the organic light emitting display device is sealed by coating the frit on a glass substrate, the device substrate and the cap are completely sealed so that the organic light emitting display device may be more effectively protected. In the method of capsule sealing using frit, frit is coated on a sealing portion of each organic light emitting display device and a laser emitting apparatus moves to emit a laser beam to the sealing portion of the organic light emitting display device so that the frit is cured for sealing.
In the above-described conventional frit sealing system, although materials for the frit have been mainly developed in order to improve the quality of sealing, the quality of a laser beam that is emitted to resolve the frit has not been developed at all. However, in the frit sealing system, the uniformity of the laser substantially dominates the distribution of the temperature of seal so that the quality of sealing is greatly changed by a slight change in the temperature. Thus, a study to secure the uniformity of the laser beam emitted to the frit is urgently needed.